This invention relates to an apparatus, a method and a system for assessing the condition of hair, in particular assessing the degree of damage in the hair.
In the hair care field it is often important to assess the condition of a consumer""s hair. In particular it is often valuable to be able to assess the degree of damage sustained by the hair. It is known that the surface of a hair fibre becomes rougher when the hair is subjected to damage, for instance as a result of brushing, bleaching, perming, colouring, etc. This reduction in smoothness is believed to result from changes in the structure of the cuticle, the outermost part of the hair fibre.
It is known to assess roughness, and by implication damage by measuring the degree of friction generated by subjecting the hair to certain conditions. For instance, ease of combing is commonly used as a measure of smoothness. In one combing test the force required to detangle, by drawing a comb through, a bundle of hair fibres is used to assess friction, roughness and damage.
EP-A-965,834 describes friction-measuring equipment for evaluating the effects of cosmetics on skin, hair, membranes and eyes. This equipment assesses friction by means of deformation of a deformable assembly on a probe.
JP 63/163143 measures the degree of damage to hair by comparing forward and reverse friction forces. These forces are measured by means of a torque meter.
JP 62/273433 measures friction between hairs by passing a fluid in turbulent flow over a bundle of hair and measuring friction by detecting pressure loss in the fluid.
It would be desirable to be able to provide systems that allow the convenient measurement and analysis of surface friction of hair. It would also be desirable to provide a means of relating this to levels of damage across a range of hair types.